A semiconductor light emitting device comprises a light emitting diode (LED) as a light source. Such a semiconductor light emitting device may include a plurality of LEDs provided on a substrate, and exhibit high luminance characteristics. Further, it becomes possible to reduce a driving current of the semiconductor light emitting device by connecting the plurality of LEDs in series, and to improve the reliability thereof as compared with a case where the plurality of LEDs is connected in parallel and driven by the same electric power. Each of the plurality of LEDs, however, has to be electrically isolated from the substrate in order to be connected in series, and thus, the bonding pads, which connect the plurality of LEDs to an external circuit, are disposed on the substrate. This may inhibit the heat dissipation through the substrate, and also make it difficult to downsize the semiconductor light emitting device.